【摘要】 为探究日光温室土壤温度偏低的原因,以传热学对流换热理论为基础,以土壤蓄热温差占温室垂直方向上最大空气温度与地面温度之差的比例(温差比例)为研究对象,针对日光温室垂直方向上的温度分布开展研究。在位于山东泰安的日光温室内,选取温室中部后墙南5.4m,距离地面0,0.1,1.1,2.1,3.1,4.27,4.37m高度处为测点,分别设置温度传感器T1～T7,地面设置热流板H1;选取试验期间土壤蓄热量高、中等、低3天试验数据,对不同高度各测点温度之间的关系进行研究;计算垂直高度上的最高空气温度,计算不同太阳辐射情况下的温差比例。试验数据验证了温室空气温度自下而上逐渐升高,然后逐渐降低;温室空气存在逆温层和对流层,存在逆温现象;逆温层上部空气密度小于下部空气密度,上部高温空气不能流动到地面,逆温层两端温差较大。计算结果表明:不同太阳辐射情况下垂直方向上最大空气温度积分与地面温度积分之差分别为890℃、770℃、175℃,土壤蓄热温差积分分别为310℃、200℃、68℃,温室散热温差积分分别为120℃、20℃、27℃,土壤蓄热时间分别为6h 55min、4h 50min、2h 20min;后墙南5.4m处逆温层、对流层高度分别为0～3.1m、3.1～4.37m;试验期间不同太阳辐射情况下温差比例分别为34.8%、26%、38.9%。结果表明:太阳辐射强度高时土壤蓄热温差和蓄热时间多于太阳辐射强度低时的土壤蓄热温差和蓄热时间;对流层空气产生自然对流,温室热量向温室外部大量散失;逆温现象造成的温差比例偏小是造成土壤总体蓄热量少、土壤温度偏低的主要原因。更多还原

【Abstract】 To explore the causes of low soil temperature in solar greenhouse, this article carried out the temperature distribution in the vertical direction with heat transfer convection theory. In the test greenhouse in Tai’an, Shandong, test points were in the middle of the greenhouse 5.4m away from the back wall and were 0m, 0.1m, 1.1m, 2.1m, 3.1m, 4.27 m, 4.37 m above the ground,and were installed temperature sensors T1-T7 on the test points respectively. Heat flow plate H1 was installed on the ground. The experimental data under high, medium and low soil heat-absorbing volume were chosen during the experiment period to study the difference among the temperature of different measuring points, and the maximum air temperature of the vertical direction and the temperature difference proportion under different solar radiation were calculated. The experimental data proved that temperature from bottom to top in vertical direction first increased, then decreased. The greenhouse air was composed of temperature inversion layer and troposphere, the greenhouse air had temperature inversion phenomenon. The air density in top side of temperature inversion layer was less than that of bottom side, high temperature air couldn’t flow from top to surface of ground, temperature difference between top and bottom was high. The analysis showed that the differences between the maximum air temperature integral and the surface temperature integral under different solar radiations in the vertical direction were 890 ℃,770℃ and 175℃, respectively. And the temperature difference integrals of the soil heat absorption were 310℃, 200℃, 68℃,respectively. The temperature difference integrals of heat dissipation in greenhouse were 120℃, 20℃ and 27℃, and the timelengths for soil absorbing heat were 6 h 55 min, 4 h 50 min and 2 h 20 min, respectively. Based on the analysis of measured data,the heights of temperature inversion layer and troposphere 5.4 meter south of the back wall were respectively 0-3.01 m and 3.01-4.37 m. During the test period the temperature difference proportions were 34.8%, 26% and 38.9%, respectively, on different heat-absorbing volume. The results showed that the temperature differences of soil heat-absorbing and the time for soil absorbing heat in the high intensity of solar radiation day were more than those of middle and low intensity of solar radiation day. The air in the troposphere produced natural convection, and the greenhouse heat was dissipated to the outside of the greenhouse largely. The low temperature difference proportion caused by temperature inversion phenomenon was the main reason that the soil has insufficient heat-absorbing volume and the soil temperature is low.更多还原